The present invention relates to an apparatus for cutting submerged metal tubes and more particularly large diameter, high thickness tubes by means of a pyrotechnic charge.
When offshore installations, such as the metal tubes of wildcat wells require, after sinking, the partial or total elimination of their submerged parts, the cutting thereof can be carried out pyrotechnically. Generally, this cutting takes place at a point which is under water and which is as close as possible to the sea bed. The cut tube portion is then removed.
At present, numerous means exist, which make it possible either to perforate, or cut a submerged tube. For this purpose, a pyrotechnic charge, mounted on a support, is lowered within the tube to the desired depth and an air pocket is formed at the level of the charge in order that the explosion takes place in air and not in water. Thus, normally, use is made of hollow charges and the efficiency of such a charge is better in air than in water.
However, the presently used means can only be used as limited depths and do not make it possible to cut large diameter, high thickness tubes. Moreover, they generally only permit a partial cutting of the tube whereas, in certain cases and in particular for dismantling offshore installations, it is necessary to obtain a complete cut in a cross-section of the tube.